Marine Thibeau has a strange new pupil in her class. A chubby and timid little girl of Irish descent, Gwendolyne communicates with a teenager who’s been dead for twenty years!Realizing that her pupil is ostracized because of her paranormal powers, the teacher takes the girl under her wing, defends her against bullies and believes in her frightening psychic premonitions. But how to reveal to the authorities that a series of murders, all foreseen by Gwendolyne, are very real and that they originate in the same long-forgotten cold case?Gendarme Thomas Moreau, assisted by the teacher, by the girl with second sight and by a weird bird watcher, embarks in an investigation that involves victims scattered in various regions of France. However, the associates must act quickly to get ahead of the killer who is about to strike for the fourth time and to murder the last man involved in the old and terrible unsolved case.